We plan to prepare chemically altered amylose to investigate (a) the role of OH groups in substrate binding to amylase and (b) the role of substrate torsion in catalysis. Types of modification are, for (a) replacement of OH by H or halogen, and for (b) periodate oxidation of 0.1 of the glucose units followed by borohydride reduction. After action of pancreatic amylase, the modified glucose units will appear in amylase-resistant oligosaccharides which we will isolate and determine their structures. Action of Bacillus macerans amylase (transglycosylase) on pullulan plus radioactive glucose gives radioactive oligosaccharides by transfer reactions. We plan to isolate these oligosaccharides and determine their structures. High resolution electron microscopy (better than 40 A resolution) is being used to explore the shape of amylopectin molecules and the very fine structure of starch granules. We will examine the role of UDPG vs ADPG as it relates to biosynthesis of amylose or amylopectin by granule-bound starch synthetase.